A limited resource client device in a television-based system, such as a set-top box without a graphics accelerator, can receive on-screen display image data and process the image data with a central processing unit to display the image as an on-screen display. For example, the client device can render a user interface with conventional four-bit on-screen display processing which will slowly render the user interface with limited color and graphic rendition.
A conventional client device also includes an MPEG hardware decoder to receive and process digital video which is rendered in a digital video plane. Digital video is processed as a sixteen-bit, true color rendition and generates an image for display much faster than an image rendered as an on-screen display. Further, an on-screen display image can be processed for display such that the on-screen image is displayed over a digital video on a display device. A conventional client device also includes a tuner that, when tuned to an analog channel, receives analog video content which is processed for display on an analog plane.
For a client device, such as a set-top box in a television-based system, there is a need to be able to generate an image formatted for display as on on-screen display image with component(s) of the client device other than with a central processing unit.